Producers urged to test for OJD

Kate MatthewsCountryman

For every farm infected with ovine Johne’s disease (OJD), at least another four go undetected, according to sheep consultant Graham Lean.

It’s a frightening statement, but one that WA sheep producers must face up to if they want to stop the spread of the wasting disease, which can go unnoticed for years.

At a series of seminars across the Great Southern last week, producers were told mortality rates averaged 6.8 per cent in infected flocks and could be as high as 20 per cent.

Speakers at the seminars included Animal Health Australia (AHA), the Department of Agriculture and Food (DAFWA) and Pfizer.

State co-ordinator for OJD Anna Erickson said 41 WA producers had confirmed OJD status, but there were likely to be more.

In January, WA’s OJD prevalence status went from low to medium, which had an impact on where sheep could be traded.

The key for WA producers is to learn from the mistakes of their Victorian counterparts, who found themselves in a similar position 10 years ago.

“Victoria didn’t vaccinate enough and take the threat seriously,” Mr Lean said.

“Where there are sheep, there will be OJD. The only way to stop the disease is to vaccinate.”

The only vaccine available to immunise against OJD is Gudair, produced by seminar host Pfizer.

In the eastern states, vaccinated stock have been attracting a $40 a head premium.

The vaccine has been shown to be 90 per cent effective through a 1ml dose, and vaccinating new lambs each season was an important preventative measure.

AHA national Johne’s disease co-ordinator David Kennedy said the message to WA producers was to take action. “You’re in a position to slow OJD and, in some cases, possibly prevent it,” he said.

Dr Kennedy said young sheep were the most susceptible to the disease, while adult sheep were the most potent source of contamination. He said paddocks could be contaminated for a long period of time.

“One of the tools to manage OJD is assessing risk,” Dr Kennedy said.

Producers have been advised to look at their flock history, the risk of contamination from neighbours and sheep purchased off-farm and put in place biosecurity measures to reduce exposure or slow the spread.

Other tools include health statements where sellers state the health of the flock including OJD status.

A sheep market assessment program for stud breeders also helps to promote flocks with a low risk and all producers can flock test for OJD.

Young sheep should be vaccinated and contaminated paddocks should be spelled by introducing a cropping phase or by introducing cattle.

AHA endemic disease manager Lorna Citer said if producers used the tools developed by the National Johne’s Disease Control Program, there was no reason why OJD could not be managed.

Ms Citer said if producers wanted a dedicated abattoir monitoring system re-established, similar to those previously carried out by the Australian Quarantine and Inspection Service, they would need to lobby processors.

Funding has been made available by AHA to help company inspectors.

Abattoir monitoring can be conducted at present, but only by one of three DAFWA inspectors at a cost to the producer.

If monitoring was put in place and undertaken by the processor, it would allow AHA to collect prevalence data for states, part of the system that Assurance Based Credit (ABC) points have been based on.

“Abattoir monitoring can pick up legions early before producers notice mortalities, and they can get ahead of the game,” Ms Citer said.

“Although they have got the disease, they are vaccinating before it has an impact on their business.

“If you are vaccinating, you can use abattoir monitoring to determine the effectiveness of your vaccination program.”

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